1. Technical Field
The present disclosure relates to handheld medical devices suitable for use in tissue ablation applications. More particularly, the present disclosure relates to medical devices with a microwave amplifier unit at the device handle, electrosurgical systems including the same, methods of directing energy to tissue using the same, and methods of manufacturing the same.
2. Discussion of Related Art
Electrosurgical instruments have become widely used by surgeons. Electrosurgery involves the application of thermal and/or electrical energy to cut, dissect, ablate, coagulate, cauterize, seal or otherwise treat biological tissue during a surgical procedure. Electrosurgery is typically performed using a handpiece including a surgical instrument (e.g., end effector or ablation probe) adapted to transmit energy to a tissue site during electrosurgical procedures, a remote electrosurgical generator operable to output energy, and a cable assembly operatively connecting the surgical instrument to the remote generator.
In various open and laparoscopic surgeries, it is necessary to coagulate, seal or weld tissues. A number of devices are available that can be used to provide high bursts of energy for short periods of time to coagulate, cauterize, cut and/or seal tissue. By utilizing an electrosurgical forceps, a surgeon can cauterize, coagulate, desiccate and/or cut tissue and/or simply reduce or slow bleeding by controlling the intensity, frequency and duration of the electrosurgical energy applied through the end effector to the tissue. The energy is generated by a remote generator and applied to the tissue via electrodes that are electrically connected via a cable assembly to the generator.
Treatment of certain diseases requires the destruction of malignant tissue growths, e.g., tumors. In the treatment of diseases such as cancer, certain types of tumor cells have been found to denature at elevated temperatures that are slightly lower than temperatures normally injurious to healthy cells. Known treatment methods, such as hyperthermia therapy, heat diseased cells to temperatures above 41° C. while maintaining adjacent healthy cells below the temperature at which irreversible cell destruction occurs. These methods may involve applying electromagnetic radiation to heat, ablate and/or coagulate tissue. There are a number of different types of electrosurgical apparatus that can be used to perform ablation procedures.
Typically, microwave apparatus for use in ablation procedures include a microwave generator that functions as an energy source and a microwave surgical instrument (e.g., microwave ablation probe) having an antenna assembly for directing the energy to the target tissue. The surgical instrument and microwave generator are typically operatively coupled by a cable assembly having a plurality of conductors for transmitting energy from the remote generator to the surgical instrument, and for communicating control, feedback and identification signals between the instrument and the remote generator. There are several types of microwave probes in use, e.g., monopole, dipole and helical, which may be used in tissue ablation applications.
A variety of types of handheld instruments utilizing electromagnetic radiation have been employed for various types of electrosurgery in a variety of types of applications. Cable assemblies are typically employed to mechanically connect the handheld instruments to remote energy sources and to serve as a propagation medium and waveguide for the radiofrequency (RF) or microwave signal. Parameters used to evaluate the electrical performance of microwave cable assemblies include attenuation of the cable (also known as insertion loss, i.e., loss of power due to inserting the cable between the source and the load), voltage standing-wave ratio (VSWR) characteristics, and the shielding of the cable's outer conductor. Stray leakage of microwave energy from the cable assembly may cause interference to deployed wireless networks, patient monitoring, and other medical equipment used in a hospital environment. Cable assemblies add cost to produce and maintain the microwave surgical instruments. Cable assemblies may also interfere with the surgeon's full freedom of movement during use of a handheld instrument to perform procedures utilizing electromagnetic radiation to treat tissue.